Safety device for electric wires



(No Model.)

A. BERNSTEIN. SAFETY DEVICE FOR ELECTRIC WIRES. No. 284,714.

6 a 6 6 M w W I. PQERS. P

UNITED STATES PATENT OEEICEQ ALEX. BERNSTEIN, OF BOSTON, MASSACHUSETTS.

SAFETY DEVICE FOR ELECTRIC WIRES.

SPECIFICATION forming part of LettersPatent No. 284,714, dated September 11, 1883.

Application filed May 22, 1883.

To (1, whom, it; may concern:

Be it known that I, ALEX. 'BERXSTEIN, of Boston, in the county of Suitolk and State of Massachusetts, have invented certain Improvements in Safety Devices for Electric Oireuits, of which the following is a specification.

The subject of my present invention is a safety device for use in electric circuits, adapted to be brought automatically into action upon the passage through the said circuits of any unduly strong electrical currents. It has for a long time been customary to introduce at suitable points in. the circuit, or in branches thereof, a piece of a very small conductor, of higher resistance than the remainder of the circuit, in order to protect instruments included in the said circuit from the destructive and otherwise detrimental effects result ing from the passage of electrical currents of abnormal strength. It is usual, especially in systems of electrical. lighting, to multiply these safety devices, interposing them wherever it may be regarded as desirable, and, while they readily permit the passage of a current of, proper strength, they become heated and fuse (thus interrupting the circuit and ending the danger) as soon as the current flowing in the circuit becomes abnormally strong; but since they are usually made of metal, it is evident that when they fuse, drops or globules of hot molten metal will fall at the point where such fusion takes place, and that, unless some provision is made to prevent, some of them are liable to produce disastrous results by falling upon the easilydamaged and combustible surroundings and burning them or otherwise causing great damage. It has heretofore been proposed to provide for this contingency by placing a suitable receptacle for the molten metal lately constituting the safety device to run or fall. into. Subsequently shells or inclosing-jackets of non-comlucting material have been made in such a way as to inclose the two ends of the main conductors and the interposed length of the salety-conductor. I improve this construction by forming thetwo ends of the conductors themselves in. such a way as to constitute a convenient receptacle wherein the melted metal. may fall. The several figures of the accompanying drawings present examples of such a construction.

Figures 1 and show different forms of the (No model.)

arrangement of the several parts, Fig. 2 be ing a plan section view of Fig. 1 on the line a; a", and Fig. 4 a similar plan section of the combination shown in Fig. 3, on the line g y.

Each of the main conductors A and B, at thejunction-point, is caused to terminate in a cup-like receptacle, and between the bottom of the interior of one of the said receptacles and a similar point on the interior surface of the other receptacle the safety-wire f is stretched. One of the cup-like terminations of the main conducting-wires is larger than the other, as shown in the figures, so that its edge is capable of being inserted within the cavity of the other, the intervening space be ing then filled up with a suitable insulating material-such as plaster-oi parisor, if preferred, separated simply by an air-space. In Figs. 1 and 2 both of the main conductors A and B terminate in cylindrical receptacles a and I), of which the upper one, a, is the smallest in diameter. The wire of high resistance f extends from one to the other, as shown, and the insulating or non-conducting intervening substance is represented by c. A closed chamber, of which 0 is the upper half, and d the lower, is thus formed, which is utilized. as a receptacle or depository for the melted metal accruing from the fusion of the fine-wire eonductor f when an injuriously-intense current passes through it.

In Fig. 3, of which A is the plan view, the cup-like terminations, instead of having a square base, as in the foregoing examples, are rounded; but otherwise there is no diit'erence from Fig. l.

A modified construction is shown in Fig. 5. In it the upper terminal cup, (1, extends nearly to the bottom of the outer cup, b, and is separated therefrom not only by the non-conducting intervening substance, 0, butalso by a nonconduct-ing annulus, g, on which the edge of the inner cup rests, the safety-wirej" being extended between the extreme interior surfaces, as in the other forms. The terminal cups of the two separated portions of the main conductor may be formed in several ways. It may, for example, be made of sheet metal and riveted or brazed to the main wire, or it may be made of cast met; lsueh as cast-ironand riveted, or in some cases, where the conductors are suiiieiently large, attached thereto by a screw-thread. The safety-wire f may also be fastenedin any desired way. It may be passed through holes in each terminal cup and riveted to the Outside of the receptacles; or it may be brazed to one and riveted to the other; or, again, it may be passed through the substance of the containingcups, through atightfitting hole, and then twisted round the main wires.

I claim- I 1. The combination, with a safety device for electric circuits, of the inclosing-receptacle therefor, the said receptacle consisting of the two cup-like terminals of the main conductor, substantially as described.

2. A severed main circuit, a fine wire constituting a safety device, uniting the severed ends of the said main circuit, and a receptacle for the same, composed of the two cup-like terminals of the said circuit, substantiallyas' and for the purposes described.

3. In a safety device for electric circuits, a protecting envelope or receptacle consisting ofcup-sha-ped cavities or expansions, constituting the ends of a severed circuit, fixed together, mouth to mouth, and insulated from one another, the said envelope being adapted described, of a piece of fine wire electrically I uniting the severed ends of the main conductors, a depository or receptacle surrounding the same, and constituted of the two severed ends of the said conductor, which are severally formed into cup-like cavities, one of the said cups being smaller than the other, and adapted to fit loosely therein, and a non-conducting intervening partition between the said cup-like extensions, mechanically uniting them, but adapted to insulate one from the other.

In testimony whereof I have signed my name to this specification, in the presence of two subscribing witnesses, this 15th day of May,A. D. 1883.

ALEX. BERNSTEIN.

Witnesses:

FRED J. F. SCHWARTZ, GEO. WILLIs PIERCE. 

